This invention relates to an air conditioning system, and more particularly, the invention relates to a distributed electronic control for an air conditioning system of an aircraft.
Air conditioning systems are typically connected to a controller that controls a refrigeration unit to obtain a desired temperature. The controls for an air conditioning system can become relatively complex, particularly for applications in aircraft. Aircraft typically incorporate numerous packs, or refrigeration units, such as turbine driven air cycle or vapor cycle turbo machines. The packs are located throughout the aircraft and deliver conditioned air to a manifold. Air is bled from the engines propelling the aircraft and is piped through a manifold to the packs.
A primary supervisory controller has been employed in aircraft to control the packs, monitor temperatures within the air conditioning system, operate trim valves controlling the flow of air from the engine to the manifold, and interface with the flight deck. The primary supervisory controller has been located in an electronics equipment bay along with electronic equipment for other aircraft systems. As a result, the size of the controller and, therefore, the capability of the controller such as system Built-In-Test (BIT), diagnostics and prognostics capability has been limited. Because the primary supervisor controller has controlled operation of the packs and other air conditioning components, large bundles of wires, frequently between 70 and 80 wires, are connected to each of the packs in the respective locations throughout the aircraft. Each wire bundle from the primary supervisor controller to the pack may be up to 70 to 80 feet in length. As a result, the wires from the primary supervisor controller to the packs account for a significant amount of weight and present reliability issues due to the large number of wires and wire connections.
The number of packs and engines varies between aircraft platforms. The electronic control for the air conditioning system does not accommodate the different number of components between platforms. As a result, significant changes to the controls are required between platforms. Therefore, what is needed is an electronic control for the air conditioning system of an aircraft that reduces the number of wires between the electronic components and increases the capability of the controllers. Similarly, another central controller has been utilized to control the bleed valves on the engines for supplying hot, pressurized air to the packs and other aircraft systems.
The present invention provides an electronic control for an air conditioning system. The system includes first and second air conditioning packs located in the aircraft remote from one another. Each pack includes a pack controller in the same location as the pack. The pack controllers produce operating instruction signals to the packs for instructing the packs to produce conditioned air in response to pack reference signals. A supervisory controller is located in aircraft, preferably in the electronics equipment bay, and is connected to each of the pack controllers. The supervisory controller produces the pack reference signal to the pack controllers. In addition to controlling the operation of the packs, the pack controllers preferably include BIT, diagnostics, and prognostics for monitoring the packs and diagnosing problems. The run of wires from the supervisory controller to the packs may be greatly reduced, from the 70 to 80 wires typically used, to under 10 wires. The distributed electronic controllers of the present invention utilized for the packs may similarly be applied to the zone trim system and the engine air bleed valves.
Accordingly, the above invention provides a distributed electronic control for the air conditioning system of an aircraft that reduces the number of wires between the electronic components and increases the capability of the controllers while providing increased system reliability, flexibility, dispatchability, maintainability due to use of common components, as well as ease of installation.